A combustor of a gas turbine includes a transition piece which sends high-temperature and high-pressure combustion gas to a turbine.
A shell plate which forms the transition piece has a structure in which cooling air is led inside, in order to prevent burnout due to exposure to high-temperature combustion gas. Specifically, a plurality of cooling air passages extending in a direction along an axis of the transition piece is formed in the shell plate, and a cooling air inlet opened to the outer periphery side of the shell plate and a cooling air outlet opened to the inner periphery side of the shell plate are formed on each of the plurality of cooling air passages. Cooling air enters from the cooling air inlet on the outer periphery side of the transition piece into the cooling air passage and then comes out from the cooling air outlet to the inner periphery side of the transition piece.
There is a concern that a crack having a linear shape or the like may be generated in the transition piece of the combustor of the gas turbine having the above-described structure due to thermal cycle fatigue, etc. during operation. As a repair method of such a crack, a repair method as described in Patent Document 1 is known. That is, the repair method includes a groove formation process of removing a crack generation portion, thereby providing a groove for welding, a clogging process of clogging up a bottom portion of the groove by welding, and a cover attachment process of mounting a cover plate on an opening portion of the groove, which is carried out after the clogging process is carried out.